The functional neuroanatomy of geriatric depression

Neural Functioning in Late-Life Depression: An Activation Likelihood Estimation Meta-Analysis

Late-life depression (LLD) is a relatively common and debilitating mental disorder, also associated with cognitive dysfunctions and an increased risk of mortality. Considering the growing elderly population worldwide, LLD is increasingly emerging as a significant public health issue, also due to the rise in direct and indirect costs borne by healthcare systems. Understanding the neuroanatomical and neurofunctional correlates of LLD is crucial for developing more targeted and effective interventions, both from a preventive and therapeutic standpoint. This ALE meta-analysis aims to evaluate the involvement of specific neurofunctional changes in the neurophysiopathology of LLD by analysing functional neuroimaging studies conducted on patients with LLD compared to healthy subjects (HCs). We included 19 studies conducted on 844 subjects, divided into 439 patients with LLD and 405 HCs. Patients with LLD, compared to HCs, showed significant hypoactivation of the right superior and medial frontal gyri (Brodmann areas (Bas) 8, 9), left cingulate cortex (BA 24), left putamen, and left caudate body. The same patients exhibited significant hyperactivation of the left superior temporal gyrus (BA 42), left inferior frontal gyrus (BA 45), right anterior cingulate cortex (BA 24), right cerebellar culmen, and left cerebellar declive. In summary, we found significant changes in activation patterns and brain functioning in areas encompassed in the cortico-limbic-striatal network in LLD. Furthermore, our results suggest a potential role for areas within the cortico-striatal-cerebellar network in the neurophysiopathology of LLD.

Lateralized grey matter volume changes in adolescents versus adults with major depression: SDM-PSI meta-analysis

The current study is the first meta-analysis to examine grey matter volume (GMV) changes in adolescents and across the lifespan in major depressive disorder (MDD). Seed-based d mapping-with permutation of subject images (SDM-PSI) has advantages over previous coordinate-based meta-analytical methods (CBMA), such as reducing bias (via the MetaNSUE algorithm) and including non-statistically significant unreported effects. SDM-PSI was used to analyze 105 whole-brain GMV voxel-based morphometry (VBM) studies comparing 6,530 individuals with MDD versus 6,821 age-matched healthy controls (HC). A laterality effect was observed in which adults with MDD showed lower GMV than adult HC in left fronto-temporo-parietal structures (superior temporal gyrus, insula, Rolandic operculum, and inferior frontal gyrus). However, these abnormalities were not statistically significant for adolescent MDD versus adolescent HC. Instead, adolescent MDD showed lower GMV than adult MDD in right temporo-parietal structures (angular gyrus and middle temporal gyrus). These regional differences may be used as potential biomarkers to predict and monitor treatment outcomes as well as to choose the most effective treatments in adolescents versus adults. Finally, due to the paucity of youth, older adult, and longitudinal studies, future studies should attempt to replicate these GMV findings and examine whether they correlate with treatment response and illness severity.

Cognitive impairment and depression: Meta-analysis of structural magnetic resonance imaging studies

Longitudinal comorbidity of depression and cognitive impairment has been reported by number of epidemiological studies but the underlying mechanisms explaining the link between affective problems and cognitive decline are not very well understood. Imaging studies have typically investigated patients with major depressive disorder (MDD) and mild cognitive impairment (MCI) separately and thus have not identified a structural brain signature common to these conditions that may illuminate potentially targetable shared biological mechanisms. We performed a meta-analysis of. 48 voxel-based morphometry (VBM) studies of individuals with MDD, MCI, and age-matched controls and demonstrated that MDD and MCI patients had shared volumetric reductions in a number of regions including the insula, superior temporal gyrus (STG), inferior frontal gyrus, amygdala, hippocampus, and thalamus. We suggest that the shared volumetric reductions in the insula and STG might reflect communication deficits and infrequent participation in mentally or socially stimulating activities, which have been described as risk factors for both MCI and MDD. We also suggest that the disease-specific structural changes might reflect the disease-specific symptoms such as poor integration of emotional information, feelings of helplessness and worthlessness, and anhedonia in MDD. These findings could contribute to better understanding of the origins of MDD-MCI comorbidity and facilitate development of early interventions.

Positron emission tomography imaging of serotonin degeneration and beta-amyloid deposition in late-life depression evaluated with multi-modal partial least squares

Depression in late-life is associated with increased risk of cognitive decline and development of all-cause dementia. The neurobiology of late-life depression (LLD) may involve both neurochemical and neurodegenerative mechanisms that are common to depression and dementia. Transgenic amyloid mouse models show evidence of early degeneration of monoamine systems. Informed by these preclinical data, the hypotheses were tested that a spatial covariance pattern of higher beta-amyloid (Aβ) and lower serotonin transporter availability (5-HTT) in frontal, temporal, and parietal cortical regions would distinguish LLD patients from healthy controls and the expression of this pattern would be associated with greater depressive symptoms. Twenty un-medicated LLD patients who met DSM-V criteria for major depression and 20 healthy controls underwent PET imaging with radiotracers for Aβ ([11C]-PiB) and 5-HTT ([11C]-DASB). A voxel-based multi-modal partial least squares (mmPLS) algorithm was applied to the parametric PET images to determine the spatial covariance pattern between the two radiotracers. A spatial covariance pattern was identified, including higher Aβ in temporal, parietal and occipital cortices associated with lower 5-HTT in putamen, thalamus, amygdala, hippocampus and raphe nuclei (dorsal, medial and pontine), which distinguished LLD patients from controls. Greater expression of this pattern, reflected in summary 5-HTT/Aβ mmPLS subject scores, was associated with higher levels of depressive symptoms. The mmPLS method is a powerful approach to evaluate the synaptic changes associated with AD pathology. This spatial covariance pattern should be evaluated further to determine whether it represents a biological marker of antidepressant treatment response and/or cognitive decline in LLD patients.

Lower regional gray matter volume in the absence of higher cortical amyloid burden in late-life depression

Late-life depression (LLD) is associated with a risk of developing Alzheimer's disease (AD). However, the role of AD-pathophysiology in LLD, and its association with clinical symptoms and cognitive function are elusive. In this study, one hundred subjects underwent amyloid positron emission tomography (PET) imaging with [¹⁸F]-flutemetamol and structural MRI: 48 severely depressed elderly subjects (age 74.1 ± 7.5 years, 33 female) and 52 age-/gender-matched healthy controls (72.4 ± 6.4 years, 37 female). The Geriatric Depression Scale (GDS) and Rey Auditory Verbal Learning Test (RAVLT) were used to assess the severity of depressive symptoms and episodic memory function respectively. Amyloid deposition was quantified using the standardized uptake value ratio. Whole-brain voxel-wise comparisons of amyloid deposition and gray matter volume (GMV) between LLD and controls were performed. Multivariate analysis of covariance was conducted to investigate the association of regional differences in amyloid deposition and GMV with clinical factors, including GDS and RAVLT. As a result, there were no significant group differences in amyloid deposition. In contrast, LLD showed significant lower GMV in the left temporal and parietal region. GMV reduction in the left temporal region was associated with episodic memory dysfunction, but not with depression severity. Regional GMV reduction was not associated with amyloid deposition. LLD is associated with lower GMV in regions that overlap with AD-pathophysiology, and which are associated with episodic memory function. The lack of corresponding associations with amyloid suggests that lower GMV driven by non-amyloid pathology may play a central role in the neurobiology of LLD presenting as a psychiatric disorder.Trial registration: European Union Drug Regulating Authorities Clinical Trials identifier: EudraCT 2009-018064-95.

Structural and functional neuroimaging of late-life depression: a coordinate-based meta-analysis

Several neuroimaging studies have investigated localized aberrations in brain structure, function or connectivity in late-life depression, but the ensuing results are equivocal and often conflicting. Here, we provide a quantitative consolidation of neuroimaging in late-life depression using coordinate-based meta-analysis by searching multiple databases up to March 2020. Our search revealed 3252 unique records, among which we identified 32 eligible whole-brain neuroimaging publications comparing 674 patients with 568 controls. The peak coordinates of group comparisons between the patients and the controls were extracted and then analyzed using activation likelihood estimation method. Our sufficiently powered analysis on all the experiments, and more homogenous subsections of the data (patients > controls, controls > patients, and functional imaging experiments) revealed no significant convergent regional abnormality in late-life depression. This inconsistency might be due to clinical and biological heterogeneity of LLD, as well as experimental (e.g., choice of tasks, image modalities) and analytic flexibility (e.g., preprocessing and analytic parameters), and distributed patterns of neural abnormalities. Our findings highlight the importance of clinical/biological heterogeneity of late-life depression, in addition to the need for more reproducible research by using pre-registered and standardized protocols on more homogenous populations to identify potential consistent brain abnormalities in late-life depression.

Subjective age, depressive symptoms, and cognitive functioning across five domains

Objective: Younger subjective age predicts better episodic memory and executive functioning performance independent of chronological age. This study examined whether subjective age is associated with performance in five cognitive domains, quantified the extent to which these relationships are mediated by depressive symptoms, and tested whether these associations are moderated by chronological age.Method: Participants in this cross-sectional study included 993 adults aged 65 and older from the Health and Retirement Study's 2016 Harmonized Cognitive Assessment Protocol. Moderated mediation models estimated direct and indirect effects of subjective age on factor scores representing episodic memory, executive functioning, language, visuoconstruction, and speed through depressive symptoms and tested whether associations differed according to chronological age.Results: Depressive symptoms explained 21-32% of the associations between subjective age and language, speed, episodic memory, and executive functioning. Chronological age moderated the indirect effect involving language, such that depressive symptoms were more strongly related to worse language performance at older chronological ages. After accounting for indirect effects, direct effects of younger subjective age remained for language and speed domains.Conclusions: This study extends research on the cognitive correlates of subjective age and demonstrates that depressive symptoms partly mediate these relationships. Subjective age may bemost strongly associated with language among individuals at older chronological ages not because they are more sensitive to the negative mental health impact of feeling older than they are but because they may be particularly vulnerable to the negative effects of depressive symptoms on language ability. Additional longitudinal research is needed to determine whether links between subjective age and cognition are causal versus predictive.

Molecular imaging of beta-amyloid deposition in late-life depression

Late-life depression (LLD) is associated with an increased risk of all-cause dementia and may involve Alzheimer's disease pathology. Twenty-one LLD patients who met the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, criteria for a current major depressive episode and 21 healthy controls underwent clinical and neuropsychological assessments, magnetic resonance imaging to measure gray matter volumes, and high-resolution positron emission tomography to measure beta-amyloid (Aβ) deposition. Clinical and neuropsychological assessments were repeated after 10-12 weeks of Citalopram or Sertraline treatment (LLD patients only). LLD patients did not differ from healthy controls in baseline neuropsychological function, although patients improved in both depressive symptoms and visual-spatial memory during treatment. Greater Aβ in the left parietal cortex was observed in LLD patients compared with controls. Greater Aβ was correlated with greater depressive symptoms and poorer visual-spatial memory, but not with improvement with treatment. The study of LLD patients with prospective measurements of mood and cognitive responses to antidepressant treatment is an opportunity to understand early neurobiological mechanisms underlying the association between depression and subsequent cognitive decline.

Intrinsic connectivity identifies the sensory-motor network as a main cross-network between remitted late-life depression- and amnestic mild cognitive impairment-targeted networks

Remitted late-life depression (rLLD) and amnestic mild cognitive impairment (aMCI) are both associated with a high risk of developing Alzheimer's disease (AD). Neurodegeneration is considered to spread within pre-existing networks. To investigate whether, in the healthy brain, there was a pre-existing cross-network between the intrinsic networks that are vulnerable to rLLD and aMCI. We performed functional connectivity analyses based on brain areas with the greatest brain neuronal activity differences in 55 rLLD, 87 aMCI, and 114 healthy controls. Intrinsic networks that were differentially vulnerable to rLLD and aMCI converged onto the sensory-motor network (SMN) in the healthy brain. These regions in the SMN within the aMCI- and rLLD-vulnerable networks played different roles in the cognitive functions. This study identifies the SMN as a cross-network between rLLD- and aMCI-vulnerable networks. The common susceptibility of these diseases to AD is likely due to the breakdown of the cross-network. The results further suggest that interventions targeting the amelioration of sensory-motor deficits in the early course of disease in individuals with AD risk may enhance patient function as AD pathology progresses.

Neurotransmitters and Neurometabolites in Late-Life Depression: A Preliminary Magnetic Resonance Spectroscopy Study at 7T

BACKGROUND

Magnetic resonance spectroscopy (MRS) methods have quantified changes in levels of neurotransmitters and neurometabolites in patients with major depression across the lifespan. The application of 7T field strengths and greater have not been a major focus of study in patients with late-life depression (LLD).

METHODS

Nine LLD patients who met DSM-IV criteria for a current major depressive episode and nine non-depressed, healthy, age-matched controls underwent clinical and neuropsychological assessment and single-voxel 7T ¹H-MRS at baseline and after 10-12 weeks of antidepressant treatment (Citalopram; patients only). Spectra were acquired from two brain regions implicated in both depressive symptoms and neuropsychological deficits in LLD, the anterior (ACC) and posterior cingulate (PCC). Levels of γ-aminobutyric acid (GABA), glutamate (Glu), glutathione (GSH), N-acetylaspartylglutamate (NAAG), N-acetylaspartate (NAA), and myo-inositol (mI) were quantified relative to total creatine (tCr) using linear-combination modeling.

RESULTS

Baseline Glu/tCr levels were not significantly different between groups. Decreased Glu/tCr levels after Citalopram treatment were observed in a subset of LLD patients. Exploratory analyses showed that LLD patients had lower NAA levels in the PCC relative to controls. Higher levels of ml in the LLD patients relative to the controls and decreases after Citalopram treatment had large effect sizes but were not statistically significant. Further, decreases in PCC Glu/tCr and increases in ACC GSH/tCr were associated with improvement in depressive symptoms.

LIMITATIONS

Sample size.

CONCLUSIONS

These preliminary results suggest a role of neurochemicals and neurometabolites in the neurobiology of LLD and antidepressant treatment response.

Impaired biophysical integrity of macromolecular protein pools in the uncinate circuit in late-life depression

Major depressive disorder is a common mood disorder in the elderly. Although the neuroanatomical abnormalities have been identified in patients with late-life depression (LLD), the precise biological basis of LLD remains largely unknown. The purpose of this study was to examine the biophysical integrity of macromolecular protein pools in the nodal regions of the "uncinate circuit," a component of fronto-limbic circuitry that is connected by the uncinate fasciculus and is critical in the regulation of mood and emotions, using novel magnetization transfer (MT) imaging. Twenty-four patients with LLD and 27 non-depressed healthy control subjects (HCs) of comparable age, sex, and race were recruited from the communities of the greater Chicago Area. The nodal regions of the uncinate circuit, i.e., bilateral amygdala, hippocampus, and lateral and medial orbitofrontal cortices (OFCs), were examined. Compared with HCs, patients with LLD had significantly lower magnetization transfer ratio (MTR), a measure of the biophysical integrity of macromolecular protein pools, in bilateral amygdala and hippocampus. The lower MTR was negatively correlated with the depression score. Moreover, the MTR of these regions decreased with age and positively correlated with neuropsychological performance in the LLD group but not in the HC group. These findings suggest that LLD is associated with compromised biophysical integrity of macromolecular protein pools in nodal regions of the uncinate circuit, and that major depression may accentuate age-related attenuation of the biophysical integrity of macromolecular protein pools in this circuit. These findings provide important new insights into the neurobiological mechanisms of the pathophysiology of LLD.

Brain Metabolic Dysfunction in Early Neuropsychiatric Symptoms of Dementia

Neuropsychiatric symptoms (NPS) including behavioral and psychiatric symptoms are common in the dementia stages of Alzheimer's disease (AD) and are associated with poorer outcomes in cognition, functional states, quality of life, and accelerated progression to severe dementia or death. NPS are also increasingly observed in the mild cognitive impairment stage of AD and may predict incipient dementia. As such, there is an emerging conceptual framework, which support NPS as early non-cognitive symptoms of dementia. [18F]fluorodeoxyglucosepositron emission tomography is a technique that is sensitive in detecting resting metabolism associated with NPS in neuropsychiatric conditions, and there is a growing body of literature evaluating the role of NPS as early indicators of brain metabolic dysfunctions in AD. In this mini-review, we examine the frequency and associations of NPS with metabolic dysfunction in the AD continuum, including preclinical, prodromal, and dementia stages of AD. We will also present the validated neurobehavioral syndrome, mild behavioral impairment describes the later life emergence of sustained NPS as an at-risk state for incident cognitive decline and dementia, and an early presentation of neurodegenerative diseases in some. Lastly, we will discuss future directions in the field so as to better understand the neurobiological basis of NPS in the early stages of the AD continuum, and their role in predicting AD pathophysiological progression and incident dementia.

Anxiety symptoms are associated with smaller insular and orbitofrontal cortex volumes in late-life depression

BACKGROUND

Increasing understanding of the neural correlates of anxiety symptoms in late-life depression (LLD) could inform the development of more targeted and effective treatments.

METHODS

Grey matter volume (GMV) was assessed with volumetric magnetic resonance imaging in a sample of 113 adults ≥60 years with MDD using the following regions of interest: amygdala, anterior cingulate cortex (ACC), insula, orbitofrontal cortex (OFC), and temporal cortex.

RESULTS

After controlling for demographic (age, sex, education) and clinical variables (antidepressant use, anxiolytic use, duration of illness, medical comorbidity, cognitive functioning), greater severity of anxiety symptoms was associated with lower GMV bilaterally in the insula, F(1,102) = 6.63, p = 0.01, and OFC, F(1,102) = 8.35, p = 0.005. By contrast, depressive symptom severity was significantly associated with lower bilateral insula volumes, F(1,102) = 6.43, p = 0.01, but not OFC volumes, F(1,102) = 5.37, p = 0.02.

LIMITATIONS

Limitations include (1) the relatively mild nature of anxiety symptoms in our sample; (2) the cross-sectional research design, which prohibits inferences of directionality; (3) the relatively homogenous demographic of the sample, and (4) the exclusion of participants with significant psychiatric comorbidity, suicidality, or cognitive impairment.

CONCLUSIONS

Decreased OFC volumes may serve as a unique biomarker of anxiety symptoms in LLD. Future longitudinal and clinical studies with long-term follow up and more diverse samples will help further elucidate the biological, psychological, and social factors affecting associations between anxiety and brain morphology in LLD.

Comparison of Quantitative Electroencephalogram During Sleep in Depressed and Non-Depressed Patients with Parkinson's Disease

BACKGROUND Depression is one of the most important factors affecting quality of life in Parkinson's patients. Most research on Parkinson's disease with depression has focused on neuroimaging, and there have been few quantitative electroencephalogram studies. Sleep is a biomarker for depression; therefore, the aim of this study was to identify differences in quantitative electroencephalograms during sleep in depressed and non-depressed patients with Parkinson's disease. MATERIAL AND METHODS We assessed 38 Parkinson's disease patients (26 depressed patients, 12 non-depressed patients) and 20 normal subjects using the Geriatric Depressive Scale for Depressive Symptoms and quantitative electroencephalogram analysis of amplitude of different frequency bands in different sleep stages using Met-lab software and Fast Fourier Transformation. RESULTS Non-rapid eye moment 2 and the Frontal 4 Electrode amplitude in the delta and theta ranges were progressively and significantly greater in the depressed-Parkinson's disease group (p<0.05) than in the control group. In the depressed Parkinson's disease group, from the comparison of non-rapid eye moment 2 and rapid eye moment, in Frontal 4 the amplitude in the delta ranges of non-rapid eye moment 2 was greater than in the non-depressed group, and in Central 3, Central 4, Occipital 1, and Occipital 2, the amplitudes in the beta ranges of rapid eye moment were greater (p<0.05) than in the non-depressed group. CONCLUSIONS The higher amplitude in theta in frontal areas in NREM2 and the higher amplitude in beta in parietal and occipital lobe areas in REM relative to NREM2 were significantly different in depressed and non-depressed patients with Parkinson's disease.

Meta-analyses of the neural mechanisms and predictors of response to psychotherapy in depression and anxiety

Understanding the neural mechanisms underlying psychological therapy could aid understanding of recovery processes and help target treatments. The dual-process model hypothesises that psychological therapy is associated with increased emotional-regulation in prefrontal brain regions and decreased implicit emotional-reactivity in limbic regions; however, research has yielded inconsistent findings. Meta-analyses of brain activity changes accompanying psychological therapy (22 studies, n = 352) and neural predictors of symptomatic improvement (11 studies, n = 293) in depression and anxiety were conducted using seed-based d mapping. Both resting-state and task-based studies were included, and analysed together and separately. The most robust findings were significant decreases in anterior cingulate/paracingulate gyrus, inferior frontal gyrus and insula activation after therapy. Cuneus activation was predictive of subsequent symptom change. The results are in agreement with neural models of improved emotional-reactivity following therapy as evidenced by decreased activity within the anterior cingulate and insula. We propose compensatory as well as corrective neural mechanisms of action underlie therapeutic efficacy, and suggest the dual-process model may be too simplistic to account fully for treatment mechanisms. More research on predictors of psychotherapeutic response is required to provide reliable predictors of response.

Regional neuronal activity in patients with relapsing remitting multiple sclerosis

OBJECTIVES

Although interferon-beta is an established drug for relapsing remitting multiple sclerosis (RRMS), its impact on neuronal activity is not well understood.

METHODS

We investigated 15 patients with RRMS by [¹⁸ F]fluorodeoxyglucose positron emission tomography (FDG-PET) to assess cerebral metabolic rate of glucose (CMR_glc ) before interferon-beta therapy. Further, we performed clinical and neuropsychological investigations. In nine patients, these investigations were repeated after 6 months of therapy. Ten healthy controls were also studied.

RESULTS

We found no significant differences in absolute CMR_glc between patients and controls, or in patients before and during treatment. However, during treatment, relative regional glucose metabolism (rCMRl_glc ) was decreased in cerebellum and increased in parts of left inferior parietal, temporo-occipital, frontal cortical areas, left striatum and right insula. In untreated patients, higher fatigue was associated with lower rCMRl_glc in portions of left posterior cingulate cortex, and higher depression was associated with lower rCMRl_glc within the left superior temporal sulcus. In the pooled sample, higher depression was associated with higher rCMRl_glc in parts of the right precuneus.

CONCLUSIONS

Our results indicate effects of IFN-beta treatment on cerebellar, cortical and subcortical neuronal function. Moreover, more severe fatigue and depression in untreated patients seem to be associated with reduced neuronal activity in left posterior cingulate cortex and left superior temporal cortex, respectively.

Advances and Barriers for Clinical Neuroimaging in Late-Life Mood and Anxiety Disorders

PURPOSE OF REVIEW

Mood and anxiety disorders are very commonly experienced by older adults and are becoming a growing concern due to the rapidly aging global population. Recent advances in neuroimaging may help in improving outcomes in late-life mood and anxiety disorders. The elucidation of mechanisms contributing to late-life mental health disorders may ultimately lead to the identification of novel therapeutic interventions. Alternatively, clinically validated imaging biomarkers may allow for the prediction of treatment response and identification of better therapeutic approaches in late-life mood and anxiety disorders.

RECENT FINDINGS

In community samples, late-life depression and late-life generalized anxiety disorder occur up to 38 and 15%, respectively, while late-life bipolar disorder is less common and occur in approximately 0.5% of the population. There are significant challenges in treating and improving outcome in late-life mood and anxiety disorders. Time to treatment response and treatment resistance are increased in older adults. Novel neuroimaging techniques have the potential to improve diagnostic and therapeutic outcome in late-life mood and anxiety disorders either through "personalized pharmacotherapy" or through identifying dysfunction regions/networks to be subsequently used for direct interventions such as transcranial magnetic stimulation. This review will provide an overview of recent literature that substantiates the potential role of neuroimaging in clinical practice, as well as the barriers that must be overcome prior to clinical translation.

Precuneus abnormalities in middle-aged to older adults with depressive symptoms: An analysis of BDI-II symptom dimensions

We recently reported age-related increases in left precuneus cortical thickness (CT) in older adults with elevated total depressive symptoms. However, it is unclear whether abnormalities in precuneus surface area (SA) are also evident and whether specific symptom dimensions of depression moderated age effects on these measurements. Seventy-three adults completed the Beck Depression Inventory - 2nd edition (BDI-II) and underwent structural neuroimaging. Measures of CT and SA were extracted from the right and left precuneus via FreeSurfer. Regression models included regions of interest as dependent variables, with age, BDI-II subscale scores (e.g., affective, cognitive, and somatic symptoms), and their interactions as independent variables, controlling for mean hemispheric thickness (for CT) or total intracranial volume (for SA). A significant age × somatic symptom interaction was found for left precuneus CT, such that elevated levels of somatic symptoms were significantly associated with age-related cortical thinning. No depressive symptom dimensions moderated the relationship between age and SA, suggesting that CT may be a more sensitive measure of brain abnormalities in middle-aged to older adults with depressive symptoms.

Is 18F-FDG-PET suitable to predict clinical response to the treatment of geriatric depression? A systematic review of PET studies

BACKGROUND

Geriatric depression is one of the most common psychiatric disorders in later life. It differs from earlier depression in its presentation, etiology, risk factors, protective factors and outcome. Positron emission tomography (PET) can be used to detect changes in neural circuitry in neuropsychiatric disorders, and several authors have assessed its role in the diagnosis and follow-up of patients with geriatric depression. We reviewed the current evidence on the use of fluorine-18-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET) in geriatric depressed patients to find predictors of treatment response.

METHODS

We searched PubMed/MEDLINE, Scopus, Embase, Cochrane Library, CINAHL and the PsycINFO databases to find relevant peer-reviewed articles on PET in geriatric depression using the search terms ('PET' or 'positron emission tomography') and ('mood' or 'affective disorder' or 'affective disorders' or 'depression' or 'dysthymia' or 'seasonal affective disorder').

RESULTS

Eleven articles comprising 128 patients were included. We extracted data on glucose uptake of depressed patients and controls at baseline and after different types of intervention (total sleep deprivation followed by a recovery sleep and treatment with selective serotonin reuptake inhibitors).

CONCLUSIONS

¹⁸F-FDG-PET showed significant alterations of glucose uptake in several brain areas, in particular the anterior cingulate cortex, which showed reduced metabolism after treatment, and was a predictor of treatment response.

Intrinsic inter-network brain dysfunction correlates with symptom dimensions in late-life depression

Prior studies have demonstrated dysfunctions within the core neurocognitive networks (the executive control [ECN], default mode [DMN] and salience [SN] networks) in late-life depression (LLD). Whether inter-network dysfunctional connectivity is present in LLD, and if such disruptions are associated with core symptom dimensions is unknown. A cross-sectional resting-state functional connectivity magnetic resonance imaging investigation was conducted of LLD (n = 39) and age- and gender-equated healthy comparison (HC) (n = 29) participants. Dual regression independent component analysis approach was used to identify components that represented the ECN, DMN and SN. The intrinsic inter-network connectivity was compared between LLD and HC participants and the relationship of inter-network connectivity abnormalities with dimensional measures was examined. Relative to HC participants, LLD subjects showed decreased inter-network connectivity between the bilateral ECN and default mode subcortical (thalamus, basal ganglia and ventral striatum) networks, and the left ECN and SN insula component; and increased inter-network connections between the left ECN and posterior DMN and salience (dorsal anterior cingulate) network components. Distinct inter-network connectivity abnormalities correlated with depression and anxiety severity, and executive dysfunction in LLD participants. LLD subjects also showed pronounced intra-network connectivity differences within the ECN, whereas fewer but significant DMN and SN disruptions were also detected. Investigating the intrinsic inter-network functional connectivity could provide a mechanistic framework to better understand the neural basis that underlies core symptom dimensions in LLD. Inter-network connectivity measures have the potential to be neuroimaging biomarkers of symptom dimensions comprising LLD, and may assist in developing symptom-specific treatment algorithms.

Neuropsychiatric subsyndromes and brain metabolic network dysfunctions in early onset Alzheimer's disease

Neuropsychiatric symptoms (NPSs) often occur in early-age-of-onset Alzheimer's disease (EOAD) and cluster into sub-syndromes (SSy). The aim of this study was to investigate the association between 18 F-FDG-PET regional and connectivity-based brain metabolic dysfunctions and neuropsychiatric SSy. NPSs were assessed in 27 EOAD using the Neuropsychiatric Inventory and further clustered into four SSy (apathetic, hyperactivity, affective, and psychotic SSy). Eighty-five percent of EOAD showed at least one NPS. Voxel-wise correlations between SSy scores and brain glucose metabolism (assessed with 18 F-FDG positron emission tomography) were studied. Interregional correlation analysis was used to explore metabolic connectivity in the salience (aSN) and default mode networks (DMN) in a larger sample of EOAD (N = 51) and Healthy Controls (N = 57). The apathetic, hyperactivity, and affective SSy were highly prevalent (>60%) as compared to the psychotic SSy (33%). The hyperactivity SSy scores were associated with increase of glucose metabolism in frontal and limbic structures, implicated in behavioral control. A comparable positive correlation with part of the same network was found for the affective SSy scores. On the other hand, the apathetic SSy scores were negatively correlated with metabolism in the bilateral orbitofrontal and dorsolateral frontal cortex known to be involved in motivation and decision-making processes. Consistent with these SSy regional correlations with brain metabolic dysfunction, the connectivity analysis showed increases in the aSN and decreases in the DMN. Behavioral abnormalities in EOAD are associated with specific dysfunctional changes in brain metabolic activity, in particular in the aSN that seems to play a crucial role in NPSs in EOAD. Hum Brain Mapp 37:4234-4247, 2016. © 2016 Wiley Periodicals, Inc.

Vascular depression consensus report - a critical update

BACKGROUND

Vascular depression is regarded as a subtype of late-life depression characterized by a distinct clinical presentation and an association with cerebrovascular damage. Although the term is commonly used in research settings, widely accepted diagnostic criteria are lacking and vascular depression is absent from formal psychiatric manuals such as the Diagnostic and Statistical Manual of Mental Disorders, 5^th edition - a fact that limits its use in clinical settings. Magnetic resonance imaging (MRI) techniques, showing a variety of cerebrovascular lesions, including extensive white matter hyperintensities, subcortical microvascular lesions, lacunes, and microinfarcts, in patients with late life depression, led to the introduction of the term "MRI-defined vascular depression".

DISCUSSION

This diagnosis, based on clinical and MRI findings, suggests that vascular lesions lead to depression by disruption of frontal-subcortical-limbic networks involved in mood regulation. However, despite multiple MRI approaches to shed light on the spatiotemporal structural changes associated with late life depression, the causal relationship between brain changes, related lesions, and late life depression remains controversial. While postmortem studies of elderly persons who died from suicide revealed lacunes, small vessel, and Alzheimer-related pathologies, recent autopsy data challenged the role of these lesions in the pathogenesis of vascular depression. Current data propose that the vascular depression connotation should be reserved for depressed older patients with vascular pathology and evident cerebral involvement. Based on current knowledge, the correlations between intra vitam neuroimaging findings and their postmortem validity as well as the role of peripheral markers of vascular disease in late life depression are discussed.

CONCLUSION

The multifold pathogenesis of vascular depression as a possible subtype of late life depression needs further elucidation. There is a need for correlative clinical, intra vitam structural and functional MRI as well as postmortem MRI and neuropathological studies in order to confirm the relationship between clinical symptomatology and changes in specific brain regions related to depression. To elucidate the causal relationship between regional vascular brain changes and vascular depression, animal models could be helpful. Current treatment options include a combination of vasoactive drugs and antidepressants, but the outcomes are still unsatisfying.

Brain levels of high-energy phosphate metabolites and executive function in geriatric depression

OBJECTIVES

Depression in late life has been associated with difficulties in cognitive processing, particularly in the domains of executive function, processing speed and memory, and increases the risk of developing dementia suggesting a neurodegenerative phenotype. Mitochondrial dysfunction is frequently an early event in neurodegenerative illnesses and may be operative in patients with late life depression. Phosphorus magnetic resonance spectroscopy (31P MRS) allows for the quantification of bioenergetic molecules produced by mitochondria.

METHODS

Ten patients with late life depression and eight normal elderly controls were studied with Stroop color and interference tests, which are widely used measures of processing speed and executive function, respectively, followed by (31P) MRS 3-dimensional chemical-shift imaging measuring levels of adenosine triphosphate, phosphocreatine, inorganic phosphate, and pH over the whole brain.

RESULTS

In all subjects, gray matter phosphocreatine was positively associated with Stroop interference. Levels of white matter adenosine triphosphate were associated with Stroop interference in subjects with late life depression but not normal elderly. There was also a complementary association between white matter inorganic phosphate and Stroop interference in late life depression patients.

CONCLUSIONS

These findings suggest two independent sources of executive function dependence on bioenergetic state in the aging brain. The dependence of executive function performance in subjects with late life depression on ATP in white matter may be associated with mitochondrial impairment and is consistent with predictions of the vascular depression hypothesis. Further research with wider neuropsychological testing targeting bioenergetic markers could help clarify the scope of these effects. Copyright © 2016 John Wiley & Sons, Ltd.

A long-term longitudinal follow-up of depressed patients treated with ECT with special focus on development of dementia

BACKGROUND

In this study, the long term effects of ECT on patients with depression were investigated through repeated rCBF and EEG measures as well as clinical characteristics over several years. The aim of the investigation was to establish an association with the eventual development of dementia.

METHOD

A cohort of forty-nine patients (21 men and 28 women) with a mean age of 61 years underwent ECT. A subsequent evaluation from medical records and three rating-scales for diagnosis of Alzheimer´s disease (AD), fronto-temporal dementia (FTD), and for vascular dementia (VaD), revealed that 17 patients (8 men and 9 women), had developed dementia. These cases were compared to the 32 patients (13 men and 19 women), who had not developed dementia.

RESULT

Initially, the dementia group, compared to those without dementia, showed a lower hemispheric CBF (left side; p=.029, right side; p=.033), and a lower mean occipital EEG frequency (p=.048). After the first ECT-series, an increase in general disorientation (p=.015), personal disorientation (p=.009), and subsequently, spatial disorientation (p=.021), were seen in the dementia group. There were no differences in the clinical response or remissions after treatment in the groups.

LIMITATIONS

The small sample-size, which did not allow for the comparison of characteristics between different dementias.

CONCLUSION

Depressed older patients who later developed dementia showed lower hemispheric mean level of CBF and EEG mean frequency before ECT and higher personal and spatial disorientation following ECT.

Applications of magnetic resonance imaging for treatment-resistant late-life depression

Late-life depression (LLD) is a growing public and global health concern with diverse clinical manifestations and etiology. This literature review summarizes neuroimaging findings associated with depression in older adults and treatment-response variability. LLD has been associated with cerebral atrophy, diminished myelin integrity, and cerebral lesions in frontostriatal-limbic regions. These associations help explain the depression-executive dysfunction syndrome observed in LLD, and support cerebrovascular burden as a pathogenic mechanism. Furthermore, this review suggests that neuroimaging determinants of treatment resistance also reflect cerebrovascular burden. Of the theoretical etiologies of LLD, cerebrovascular burden may mediate treatment resistance. This review proposes that neuroimaging has the potential for clinical translation. Controlled trials may identify neuroimaging biomarkers that may inform treatment by identifying depressed adults likely to remit with pharmacotherapy, identifying individualized therapeutic dose, and facilitating earlier treatment response measures. Neuroimaging also has the potential to similarly inform treatment response variability from treatment with aripiprazole (dopamine modulator) and buprenorphine (opiate modulator).

Amygdala network dysfunction in late-life depression phenotypes: Relationships with symptom dimensions

The amygdala, a crucial hub of the emotional processing neural system, has been implicated in late-life depression (LLD) pathophysiology. However, the overlapping and diverging amygdala network function abnormalities underlying two clinical LLD phenotypes (i.e., LLD alone and LLD with mild cognitive impairment [LLD-MCI]) are unknown. The aim of this study is to investigate the amygdala functional connectivity (FC) differences between LLD alone, LLD-MCI and healthy controls, and to examine the relationships between amygdala network dysfunction and symptom dimensions. A resting-state functional connectivity magnetic resonance imaging study was conducted to probe amygdala FC in a total of 63 elderly participants (LLD [n = 22], LLD-MCI [n = 15], and age- and gender-equated healthy older adults [n = 26]) using a seed-based voxelwise R-fcMRI approach. LLD-only adults showed increased FC in the posterior default mode and vermis, and diminished connections in the fronto-parietal, salience and temporal areas, relative to controls. The LLD-MCI participants showed diminished FC in the default mode, cognitive control, salience and visual regions, whereas increased FC was limited to lateral parietal cortex compared with healthy controls. The LLD-MCI group also showed diminished FC in the occipital and posterior default mode areas, relative to the LLD-only group. Distinct amygdala FC abnormalities that explain depressive and anxiety symptom severity, and executive functioning were identified. The amygdala FC impairments may distinguish LLD phenotypes. These functional network abnormalities may also explain the heterogeneity seen in the LLD clinical presentations.

A long-term follow-up of clinical response and regional cerebral blood flow changes in depressed patients treated with ECT

BACKGROUND

Depression is the leading cause of disability worldwide and electroconvulsive therapy (ECT) is the most potent therapy. We investigated the clinical response and regional cerebral blood flow changes in depressed in patients treated with (ECT) in a repeated longitudinal study.

METHOD

Forty-nine patients (21 men and 28 women) with a mean age 61 years underwent ECT. Forty-one patients grading improvement after the initial ECT-series (responder group) were compared with eight, grading no improvement (non-responder group). The patients underwent neuropsychiatric ratings, measure of clinical response (defined as ≥50% reduction of pre-treatment depression score) and measure of regional cerebral blood flow (rCBF).

RESULTS

The responder group had an initial 60-82%, and the non-responder group a 30-64% clinical response throughout the follow-up. The non-responder group showed more reported depression (p=.003), and vegetative anxiety (p=.024), with a generally higher left temporal rCBF (p=.045).

LIMITATIONS

The retrospective approach and the small sample-size.

CONCLUSION

Patients with no subjective improvement after ECT had lesser objective clinical response, more sustained reported depression with anxiety features, and higher left temporal rCBF.

Depressive symptoms accelerate cognitive decline in amyloid-positive MCI patients

PURPOSE

Late-life depression even in subsyndromal stages is strongly associated with Alzheimer's disease (AD). Furthermore, brain amyloidosis is an early biomarker in subjects who subsequently suffer from AD and can be sensitively detected by amyloid PET. Therefore, we aimed to compare amyloid load and glucose metabolism in subsyndromally depressed subjects with mild cognitive impairment (MCI).

METHODS

[(18)F]AV45 PET, [(18)F]FDG PET and MRI were performed in 371 MCI subjects from the Alzheimer's Disease Neuroimaging Initiative Subjects were judged β-amyloid-positive (Aβ+; 206 patients) or β-amyloid-negative (Aβ-; 165 patients) according to [(18)F]AV45 PET. Depressive symptoms were assessed by the Neuropsychiatric Inventory Questionnaire depression item 4. Subjects with depressive symptoms (65 Aβ+, 41 Aβ-) were compared with their nondepressed counterparts. Conversion rates to AD were analysed (mean follow-up time 21.5 ± 9.1 months) with regard to coexisting depressive symptoms and brain amyloid load.

RESULTS

Aβ+ depressed subjects showed large clusters with a higher amyloid load in the frontotemporal and insular cortices (p < 0.001) with coincident hypermetabolism (p < 0.001) in the frontal cortices than nondepressed subjects. Faster progression to AD was observed in subjects with depressive symptoms (p < 0.005) and in Aβ+ subjects (p < 0.001). Coincident depressive symptoms additionally shortened the conversion time in all Aβ+ subjects (p < 0.005) and to a greater extent in those with a high amyloid load (p < 0.001).

CONCLUSION

Our results clearly indicate that Aβ+ MCI subjects with depressive symptoms have an elevated amyloid load together with relative hypermetabolism of connected brain areas compared with cognitively matched nondepressed individuals. MCI subjects with high amyloid load and coexistent depressive symptoms are at high risk of faster conversion to AD.

Structural imaging in late-life depression: association with mood and cognitive responses to antidepressant treatment

OBJECTIVES

Recent positron emission tomography studies of cerebral glucose metabolism have identified the functional neural circuitry associated with mood and cognitive responses to antidepressant treatment in late life depression (LLD). The structural alterations in these networks are not well understood. The present study used magnetic resonance (MR) imaging and voxel-based morphometry to evaluate the association between gray matter volumes and changes in mood symptoms and cognitive function with treatment with the antidepressant citalopram.

DESIGN

Open-label trial with baseline brain MR scan. Mood and cognitive assessments performed at baseline and during citalopram treatment.

SETTING

Outpatient clinics of an academic medical center.

PARTICIPANTS

17 previously unmedicated patients age 55 years or older with a major depressive episode and 17 non-depressed comparison subjects.

INTERVENTION

12-week trial of flexibly dosed citalopram.

MEASUREMENTS

Gray matter volumes, Hamilton Depression Rating Scale, California Verbal Learning Test, Delis-Kaplan Executive Function System.

RESULTS

In LLD, higher gray matter volumes in the cingulate gyrus, superior and middle frontal gyri, middle temporal gyrus, and precuneus was associated with greater mood improvement. Higher gray matter volumes in primarily frontal areas were associated with greater improvement in verbal memory and verbal fluency performance.

CONCLUSIONS

Associations with antidepressant induced improvements in mood and cognition were observed in several brain regions previously correlated with normalization of glucose metabolism after citalopram treatment in LLD. Future studies will investigate molecular mechanisms underlying these associations (e.g., beta-amyloid, inflammation, glutamate).

FMRI activation during executive function predicts response to cognitive behavioral therapy in older, depressed adults

OBJECTIVES

To test our hypothesis that pre-treatment executive function and brain regional activation during executive function would discriminate between responders and non-responders to cognitive behavioral therapy (CBT) in elderly depressed outpatients.

DESIGN

Clinical cohort study.

SETTING

University-affiliated hospital.

PARTICIPANTS

Sixty outpatients (age 59 years and older) completed 12 weeks of CBT between July 2010 and December 2011. Forty-four completed fMRI procedures.

MEASUREMENTS

The main outcome consisted of a conversion from a clinical diagnosis (Mini-International Neuropsychiatric Interview) of depression to no clinical diagnosis of depression or a significant improvement in diagnostic criteria. Brain activation measured by functional magnetic resonance imaging during the Wisconsin Card Sorting task (WCST) was the primary predictor variable.

RESULTS

67% of patients had a positive response to CBT. Decreased activation in the left inferior frontal triangle and right superior frontal gyrus as well as increased activity in the right middle frontal gyrus and left superior frontal gyrus predicted a positive response to CBT. Demographic and neurocognitive measures of WCST performance were not significant predictors of a positive CBT outcome, whereas the measure of WCST-induced activity in the prefrontal cortex was a significant predictor.

CONCLUSIONS

These data are among the first to suggest that measures of prefrontal brain activation during executive functioning predict response to CBT in older adults. Further exploration of the specific underlying processes that these prefrontal cortical regions are engaging that contributes to better CBT outcomes is warranted in larger, randomized studies.

Cerebral metabolism in major depressive disorder: a voxel-based meta-analysis of positron emission tomography studies

BACKGROUND

Major depressive disorder (MDD) is a common mental illness with high lifetime prevalence close to 20%. Positron emission tomography (PET) studies have reported decreased prefrontal, insular and limbic cerebral glucose metabolism in depressed patients compared with healthy controls. However, the literature has not always been consistent. To evaluate current evidence from PET studies, we conducted a voxel-based meta-analysis of cerebral metabolism in MDD.

METHOD

Data were collected from databases including PubMed and Web of Science, with the last report up to April 2013. Voxel-based meta-analyses were performed using the revised activation likelihood estimation (ALE) software.

RESULTS

Ten whole-brain-based FDG-PET studies in MDD were included in the meta-analysis, comprising 188 MDD patients and 169 healthy controls. ALE analyses showed the brain metabolism in bilateral insula, left lentiform nucleus putamen and extra-nuclear, right caudate and cingulate gyrus were significantly decreased. However, the brain activity in right thalamus pulvinar and declive of posterior lobe, left culmen of vermis in anterior lobe were significantly increased in MDD patients.

CONCLUSION

Our meta-analysis demonstrates the specific brain regions where possible dysfunctions are more consistently reported in MDD patients. Altered metabolism in insula, limbic system, basal ganglia, thalamus, and cerebellum and thus these regions are likely to play a key role in the pathophysiology of depression.

Brain grey matter volume alterations in late-life depression

BACKGROUND

Voxel-based morphometry (VBM) studies have demonstrated that grey matter abnormalities are involved in the pathophysiology of late-life depression (LLD), but the findings are inconsistent and have not been quantitatively reviewed. The aim of the present study was to conduct a meta-analysis that integrated the reported VBM studies, to determine consistent grey matter alterations in individuals with LLD.

METHODS

A systematic search was conducted to identify VBM studies that compared patients with LLD and healthy controls. We performed a meta-analysis using the effect size signed differential mapping method to quantitatively estimate regional grey matter abnormalities in patients with LLD.

RESULTS

We included 9 studies with 11 data sets comprising 292 patients with LLD and 278 healthy controls in our meta-analysis. The pooled and subgroup meta-analyses showed robust grey matter reductions in the right lentiform nucleus extending into the parahippocampus, the hippocampus and the amygdala, the bilateral medial frontal gyrus and the right subcallosal gyrus as well as a grey matter increase in the right lingual gyrus. Meta-regression analyses showed that mean age and the percentage of female patients with LLD were not significantly related to grey matter changes.

LIMITATIONS

The analysis techniques, patient characteristics and clinical variables of the studies included were heterogeneous, and most participants were medicated.

CONCLUSION

The present meta-analysis is, to our knowledge, the first to overcome previous inconsistencies in the VBM studies of LLD and provide robust evidence for grey matter alterations within fronto-striatal-limbic networks, thereby implicating them in the pathophysiology of LLD. The mean age and the percentage of female patients with LLD did not appear to have a measurable impact on grey matter changes, although we cannot rule out the contributory effects of medication.

Assessing regional cerebral blood flow in depression using 320-slice computed tomography

While there is evidence that the development and course of major depressive disorder (MDD) symptomatology is associated with vascular disease, and that there are changes in energy utilization in the disorder, the extent to which cerebral blood flow is changed in this condition is not clear. This study utilized a novel imaging technique previously used in coronary and stroke patients, 320-slice Computed-Tomography (CT), to assess regional cerebral blood flow (rCBF) in those with MDD and examine the pattern of regional cerebral perfusion. Thirty nine participants with depressive symptoms (Hamilton Depression Rating Scale 24 (HAMD24) score > 20, and Self-Rating Depression Scale (SDS) score > 53) and 41 healthy volunteers were studied. For all subjects, 3 ml of venous blood was collected to assess hematological parameters. Transcranial Doppler (TCD) ultrasound was utilized to measure parameters of cerebral artery rCBFV and analyse the Pulsatility Index (PI). 16 subjects (8 =  MDD; 8 =  healthy) also had rCBF measured in different cerebral artery regions using 320-slice CT. Differences among groups were analyzed using ANOVA and Pearson's tests were employed in our statistical analyses. Compared with the control group, whole blood viscosity (including high\middle\low shear rate)and hematocrit (HCT) were significantly increased in the MDD group. PI values in different cerebral artery regions and parameters of rCBFV in the cerebral arteries were decreased in depressive participants, and there was a positive relationship between rCBFV and the corresponding vascular rCBF in both gray and white matter. rCBF of the left gray matter was lower than that of the right in MDD. Major depression is characterized by a wide range of CBF impairments and prominent changes in gray matter blood flow. 320-slice CT appears to be a valid and promising tool for measuring rCBF, and could thus be employed in psychiatric settings for biomarker and treatment response purposes.

Heartsick: psychiatric and inflammatory implications of cerebromicrovascular disease

BACKGROUND

Cerebromicrovascular disease (CMVD) strikes 87% of the population older than 65 years and is linked to an increased risk of ischemic stroke, depression, cognitive impairment, and Alzheimer's disease. Despite the wealth of knowledge on the consequences to the body stemming from poor vascular health, little focus has been placed on the consequences to the brain.

DESIGN

In this review, we present the preclinical and clinical evidence that supports the role of CMVD in behavioral dysfunction, argues for a clinical need for better recognition of the vascular depression phenotype, and calls for a more integrative translational approach to CMVD.

RESULTS AND CONCLUSIONS

Although the concept of cerebrovascular-induced behavioral change has existed for over 100 years, the difficulty of diagnosis, the slow progression of CMVD, and the lack of causative data have led to an underestimation of the patient population and poor treatment strategies. Preclinical studies have focused on the use of microsphere embolic models and vascular inflammation models to assess the mechanisms of, and treatment options for, CMVD. Though preclinical models provide support for correlative data collected in the clinic, translational reciprocity has not been established. The lack of clinical appreciation for the role of cerebrovascular health in brain function may result in missed diagnoses and inadequate treatment of underlying cardiovascular disease. Enhanced recognition of symptoms and disease presentation will allow for earlier prevention, detection, and identification of novel targets for drug development and other intervention strategies.

The relationship between fasting serum glucose and cerebral glucose metabolism in late-life depression and normal aging

Evidence exists for late-life depression (LLD) as both a prodrome of and risk factor for Alzheimer׳s disease (AD). The underlying neurobiological mechanisms are poorly understood. Impaired peripheral glucose metabolism may explain the association between depression and AD given the connection between type 2 diabetes mellitus with both depression and AD. Positron emission tomography (PET) measures of cerebral glucose metabolism are sensitive to detecting changes in neural circuitry in LLD and AD. Fasting serum glucose (FSG) in non-diabetic young (YC; n=20) and elderly controls (EC; n=12) and LLD patients (n=16) was correlated with PET scans of cerebral glucose metabolism on a voxel-wise basis. The negative correlations were more extensive in EC versus YC and in LLD patients versus EC. Increased FSG correlated with decreased cerebral glucose metabolism in LLD patients to a greater extent than in EC in heteromodal association cortices involved in mood symptoms and cognitive deficits observed in LLD and dementia. Negative correlations in YC were observed in sensory and motor regions. Understanding the neurobiological consequences of diabetes and associated conditions will have substantial public health significance given that this is a modifiable risk factor for which prevention strategies could have an important impact on lowering dementia risk.

Brain network dysfunction in late-life depression: a literature review

As a common psychiatric disorder in the growing geriatric population, late-life depression (LLD) has a negative impact on the cognitive, affective, and somatic domains of the lives of the elderly individuals. Accumulating evidence from the structural and functional imaging studies on LLD supports a "network dysfunction model" rather than a "lesion pathology model" for understanding the underlying biological mechanism in this mental disorder. In this work, we used network dysfunction model as a conceptual framework for reviewing recent neuroimaging findings in LLD. Our focus was on 4 major neurocircuits that have been shown to be involved in LLD: default mood network, cognitive control network, affective/frontolimbic network, and corticostriatal circuits. Findings of LLD-related gray and white matter structural abnormalities and resting-state and task-based functional changes were discussed for each network separately. We extended our review by summarizing the latest works that apply graph theory-based network analysis techniques for testing alterations in whole-brain network properties associated with LLD.

Positron emission tomography molecular imaging in late-life depression

Molecular imaging represents a bridge between basic and clinical neuroscience observations and provides many opportunities for translation and identifying mechanisms that may inform prevention and intervention strategies in late-life depression (LLD). Substantial advances in instrumentation and radiotracer chemistry have resulted in improved sensitivity and spatial resolution and the ability to study in vivo an increasing number of neurotransmitters, neuromodulators, and, importantly, neuropathological processes. Molecular brain imaging studies in LLD will be reviewed, with a primary focus on positron emission tomography. Future directions for the field of molecular imaging in LLD will be discussed, including integrating molecular imaging with genetic, neuropsychiatric, and cognitive outcomes and multimodality neuroimaging.

Graph theory analysis of cortical-subcortical networks in late-life depression

OBJECTIVES

Late-life major depression (LLD) is characterized by distinct epidemiologic and psychosocial factors, as well as medical comorbidities that are associated with specific neuroanatomical differences. The purpose of this study was to use interregional correlations of cortical and subcortical volumes to examine cortical-subcortical structural network properties in subjects with LLD compared with healthy comparison subjects.

METHODS

This was a cross-sectional neuroimaging study conducted in the general community. We recruited 73 healthy elderly comparison subjects and 53 subjects with LLD who volunteered in response to advertisements. Brain network connectivity measures were generated by correlating regional volumes after controlling for age, gender, and intracranial volume by using the Brain Connectivity Toolbox.

RESULTS

Results for overall network strength revealed that LLD networks showed a greater magnitude of associations for both positive and negative correlation weights compared with healthy elderly networks. LLD networks also demonstrated alterations in brain network structure compared with healthy comparison subjects. LLD networks were also more vulnerable to targeted attacks compared with healthy elderly comparison subjects, and this vulnerability was attenuated when controlling for white matter alterations.

CONCLUSIONS

Overall, this study demonstrates that cortical-subcortical network properties are altered in LLD and may reflect the underlying neuroanatomical vulnerabilities of the disorder.

Late-life depression, mild cognitive impairment and hippocampal functional network architecture

Late-life depression (LLD) and amnestic mild cognitive impairment (aMCI) are associated with medial temporal lobe structural abnormalities. However, the hippocampal functional connectivity (HFC) similarities and differences related to these syndromes when they occur alone or coexist are unclear. Resting-state functional connectivity MRI (R-fMRI) technique was used to measure left and right HFC in 72 elderly participants (LLD [n = 18], aMCI [n = 17], LLD with comorbid aMCI [n = 12], and healthy controls [n = 25]). The main and interactive relationships of LLD and aMCI on the HFC networks were determined, after controlling for age, gender, education and gray matter volumes. The effects of depressive symptoms and episodic memory deficits on the hippocampal functional connections also were assessed. While increased and decreased left and right HFC with several cortical and subcortical structures involved in mood regulation were related to LLD, aMCI was associated with globally diminished connectivity. Significant LLD-aMCI interactions on the right HFC networks were seen in the brain regions critical for emotion processing and higher-order cognitive functions. In the interactive brain regions, LLD and aMCI were associated with diminished hippocampal functional connections, whereas the comorbid group demonstrated enhanced connectivity. Main and interactive effects of depressive symptoms and episodic memory performance were also associated with bilateral HFC network abnormalities. In conclusion, these findings indicate that discrete hippocampal functional network abnormalities are associated with LLD and aMCI when they occur alone. However, when these conditions coexist, more pronounced vulnerabilities of the hippocampal networks occur, which may be a marker of disease severity and impending cognitive decline. By utilizing R-fMRI technique, this study provides novel insights into the neural mechanisms underlying LLD and aMCI in the functional network level.

Patterns of reduced cortical thickness in late-life depression and relationship to psychotherapeutic response

OBJECTIVE

Cortical atrophy has been associated with late-life depression (LLD) and recent findings suggest that reduced right hemisphere cortical thickness is associated with familial risk for major depressive disorder, but cortical thickness abnormalities in LLD have not been explored. Furthermore, cortical atrophy has been posited as a contributor to poor antidepressant treatment response in LLD, but the impact of cortical thickness on psychotherapy response is unknown. This study was conducted to evaluate patterns of cortical thickness in LLD and in relation to psychotherapy treatment outcomes.

METHODS

Participants included 22 individuals with LLD and 12 age-matched comparison subjects. LLD participants completed 12 weeks of psychotherapy and treatment response was defined as a 50% reduction in depressive symptoms. All participants underwent magnetic resonance imaging of the brain, and cortical mapping of gray matter tissue thickness was calculated.

RESULTS

LLD individuals demonstrated thinner cortex than controls prominently in the right frontal, parietal, and temporal brain regions. Eleven participants (50%) exhibited positive psychotherapy response after 12 weeks of treatment. Psychotherapy nonresponders demonstrated thinner cortex in bilateral posterior cingulate and parahippocampal cortices, left paracentral, precuneus, cuneus, and insular cortices, and the right medial orbitofrontal and lateral occipital cortices relative to treatment responders.

CONCLUSIONS

Our findings suggest more distributed right hemisphere cortical abnormalities in LLD than have been previously reported. In addition, our findings suggest that reduced bilateral cortical thickness may be an important phenotypic marker of individuals at higher risk for poor response to psychotherapy.

Recent advances in neuroimaging biomarkers in geriatric psychiatry

Neuroimaging, both structural and functional, serve as useful adjuncts to clinical assessment, and can provide objective, reliable means of assessing disease presence and process in the aging population. In the following review we briefly explain current imaging methodologies. Then, we analyze recent developments in developing neuroimaging biomarkers for two highly prevalent disorders in the elderly population- Alzheimer's disease (AD) and late-life depression (LLD). In AD, efforts are focused on early diagnosis through in vivo visualization of disease pathophysiology. In LLD, recent imaging evidence supports the role of white matter ischemic changes in the pathogenesis of depression in the elderly, the "vascular hypothesis." Finally, we discuss potential roles for neuroimaging biomarkers in geriatric psychiatry in the future.

Longitudinal studies of cerebral glucose metabolism in late-life depression and normal aging

OBJECTIVE

Late-life depression (LLD) has a substantial public health impact and is both a risk factor for and a prodrome of dementia. Positron emission tomography (PET) studies of cerebral glucose metabolism have demonstrated sensitivity in evaluating neural circuitry involved in depression, aging, incipient cognitive decline, and dementia. The present study evaluated the long term effects of a course of antidepressant treatment on glucose metabolism in LLD patients.

METHODS

Nine LLD patients and seven non-depressed control subjects underwent clinical and cognitive evaluations as well as brain magnetic resonance imaging and PET studies of cerebral glucose metabolism at baseline, after 8 weeks of treatment with citalopram for a major depressive episode (patients only), and at an approximately 2-year follow-up.

RESULTS

The majority of LLD patients were remitted at follow-up (7/9). Neither patients nor controls showed significant cognitive decline. The patients showed greater increases in glucose metabolism than the controls in regions associated with mood symptoms (anterior cingulate and insula). Both groups showed decreases in metabolism in posterior association cortices implicated in dementia.

CONCLUSIONS

Longitudinal changes in cerebral glucose metabolism are observed in controls and in LLD patients without significant cognitive decline that are more extensive than the decreases in brain volume. Longer duration follow-up studies and the integration of other molecular imaging methods will have implications for understanding the clinical and neurobiological significance of these metabolic changes.

Effect of Bcl-2 rs956572 SNP on regional gray matter volumes and cognitive function in elderly males without dementia

The Bcl-2 gene is a major regulator of neural plasticity and cellular resilience. A single-nucleotide polymorphism (SNP) in the Bcl-2 gene, Bcl-2 rs956572, significantly modulates the expression of Bcl-2 protein and cellular vulnerability to apoptosis. This study investigated the association between the Bcl-2 rs956572 SNP and brain structural abnormalities in non-demented elders, and to test the relationship between neuropsychological performance and regional gray matter (GM) volumes. Our sample comprised 97 non-demented elderly men with a mean age of 80.6 ± 5.6 years (range, 65 to 92 years). Cognitive test results, magnetic resonance imaging, and genotyping of Bcl-2 rs956572 were examined for each subject. The differences in regional GM volumes between G homozygotes and A-allele carriers were tested using optimized voxel-based morphometry. Subjects with G homozygotes exhibited significantly worse performance in the language domain of the Cognitive Abilities Screening Instrument (CASI; p = 0.009). They also showed significantly smaller GM volumes in the right middle temporal gyrus (MTG) (BA 21), but larger GM volumes in the left precuneus (BA 31), right lingual gyrus (BA 18), and left superior occipital gyrus (BA 19) relative to A-allele carriers (p < 0.001). A trend toward a positive correlation between right MTG GM volumes and the language domain of CASI was also evident (r = 0.181; p = 0.081). The findings suggest that Bcl-2 rs956572 SNP may modulate cognitive function and regional GM volume in non-demented elderly men, and that this polymorphism may affect language performance through its effect on the right MTG.

A systematic review and meta-analysis of magnetic resonance imaging studies in late-life depression

Gray matter abnormalities within frontal-subcortical and limbic networks are hypothesized to play a key role in the pathophysiology of late-life depression. In this work, gray matter abnormalities in late-life depression are examined in a systematic review and meta-analysis of magnetic resonance imaging studies. In the systematic review, 27 articles were identified that compared participants with late-life depression with comparison group participants, and 17 studies were suitable for inclusion in meta-analyses of volumes of the whole brain, orbitofrontal cortex, caudate, hippocampus, putamen, and thalamus. Volume reductions were detected in 7 of 15 comparisons of the hippocampus and a meta-analysis revealed a significant, but small, effect size. Although examined by fewer studies, meta-analyses also revealed significant volume reductions in the orbitofrontal cortex, putamen, and thalamus. A more systematic and comprehensive analysis of the global distribution of gray matter abnormalities, and an examination of subcortical abnormalities were identified as key areas for future research.

Organic bases of late-life depression: a critical update

Late-life depression (LLD) is frequently associated with cognitive impairment and increases the risk of subsequent dementia. Cerebrovascular disease, deep white matter lesions, Alzheimer disease (AD) and dementia with Lewy bodies (DLB) have all been hypothesized to contribute to this increased risk, and a host of studies have looked at the interplay between cerebrovascular disease and LLD. This has resulted in new concepts of LLD, such as "vascular depression", but despite multiple magnetic resonance imaging (MRI) studies in this field, the relationship between structural changes in human brain and LLD is still controversial. While pathological findings of suicide in some elderly persons revealed multiple lacunes, small vessel cerebrovascular disease, AD-related lesions or multiple neurodegenerative pathologies, recent autopsy data challenged the role of subcortical lacunes and white matter lesions as major morphological substrates of depressive symptoms as well as poorer executive function and memory. Several neuropathological studies, including a personal clinico-pathological study in a small cohort of elderly persons with LLD and age-matched controls confirmed that lacunes, periventricular and deep white matter demyelination as well as AD-related lesions are usually unrelated to the occurrence of LLD. In the same line, neuropathological data show that early-onset depression is not associated with an acceleration of age-related neurodegenerative changes. Very recent data on the critical role of glia-modulating neuronal dysfunction and degeneration in depression are discussed.

Abnormal regional spontaneous neural activity in first-episode, treatment-naive patients with late-life depression: a resting-state fMRI study

BACKGROUND

The previous resting perfusion or task-based studies have provided evidence of functional changes in the brains of patients with late-life depression (LLD). Little is known, so far, about the changes in the spontaneous brain activity in LLD during the resting state. The aim of this study was to investigate the spontaneous neural activity in first-episode, treatment-naive patients with LLD by using resting-state functional magnetic resonance imaging (fMRI).

METHODS

A novel analytical method, coherence-based regional homogeneity (Cohe-ReHo), was used to assess regional spontaneous neural activity during the resting state in 15 first-episode, treatment-naive patients with LLD and 15 age- and gender-matched healthy controls.

RESULTS

Compared to the healthy controls, the LLD group showed significantly decreased Cohe-ReHo in left caudate nucleus, right anterior cingulate gyrus, left dorsolateral prefrontal cortex, right angular gyrus, bilateral medial prefrontal cortex, and right precuneus, while significantly increased Cohe-ReHo in left cerebellum posterior lobe, left superior temporal gyrus, bilateral supplementary motor area, and right postcentral gyrus (p<0.005, corrected for multiple comparisons).

CONCLUSIONS

These findings indicated abnormal spontaneous neural activity was distributed extensively in first-episode, treatment-naive patients with LLD during the resting state. Our results might supply a novel way to look into the underlying pathophysiology mechanisms of patients with LLD.

The role of glia in late-life depression

Late-life depression (LLD) has a complex and multifactoral etiology. There is growing interest in elucidating how glia, acting alone or as part of a glial-neuronal network, may contribute to the pathophysiology of depression. In this paper, we explore results from neuroimaging studies showing gray-matter volume loss in key frontal and subcortical structures implicated in LLD, and present the few histological studies that have examined neuronal and glial densities in these regions. Compared to results in younger people with depression, there appear to be age-dependent differences in neuronal pathology but the changes in glial pathology may be more subtle, perhaps reflecting a longer-term compensatory gliosis to earlier damage. We then consider the mechanisms by which both astrocytes and microglia may mediate and modulate neuronal dysfunction and possible degeneration in depression. These include a critical role in the response to peripheral inflammation and central microglial activation, as well as a key role in glutamate metabolism. Advances in our understanding of glia are highlighted, including the role of microglia as "electricians" of the brain and astrocytes as key communicating cells, an integral part of the tripartite synapse. Finally, implications for clinicians are discussed, including the consideration of glia as biomarkers for LLD and incorporation of glia into future therapeutic strategies.

Neural correlates associated with cognitive decline in late-life depression

OBJECTIVES

Persistent cognitive impairment (PCI) after remission of depressive symptoms is a major adverse outcome of late-life depression (LLD). The purpose of this study was to examine neural substrates associated with PCI in LLD.

DESIGN

Longitudinal study.

SETTING

Outpatient depression treatment study at Duke University.

PARTICIPANTS

Twenty-three patients with LLD completed a 2-year follow-up study, and were in a remitted or partially remitted state at Year 2.

METHODS

At first entry to the study (Year 0), all participants had a functional magnetic resonance imaging scan while performing an emotional oddball task. For the purpose of this report, the primary functional magnetic resonance imaging outcome was brain activation during target detection, which is a measure of executive function. The Consortium to Establish a Registry for Alzheimer's Disease neuropsychological battery was used to assess cognitive status yearly, and the Montgomery-Åsberg Depression Rating Scale was used to assess severity of depression at Year 0 and every 6 months thereafter for 2 years. We investigated changes in brain activation at Year 0 associated with PCI over 2 years.

RESULTS

Patients with PCI at the 2-year follow-up date had significantly decreased activation at Year 0 in the dorsal anterior cingulate cortex, hippocampus, inferior frontal cortex, and insula compared to non-PCI patients.

CONCLUSIONS

Our results suggest individuals who have LLD with PCI have decreased activation in the similar neural networks associated with the development of Alzheimer disease among nondepressed individuals. Measuring neural activity in these regions in individuals with LLD may help identify patients at-risk for cognitive impairment.

Mindfulness-based stress reduction, mindfulness-based cognitive therapy, and Zen meditation for depression, anxiety, pain, and psychological distress

Mindfulness has been described as a practice of learning to focus attention on moment-bymoment experience with an attitude of curiosity, openness, and acceptance. Mindfulness practices have become increasingly popular as complementary therapeutic strategies for a variety of medical and psychiatric conditions. This paper provides an overview of three mindfulness interventions that have demonstrated effectiveness for psychiatric symptoms and/or pain. The goal of this review is to provide a synopsis that practicing clinicians can use as a clinical reference concerning Zen meditation, mindfulness-based stress reduction (MBSR), and mindfulness-based cognitive therapy (MBCT). All three approaches originated from Buddhist spiritual practices, but only Zen is an actual Buddhist tradition. MBSR and MBCT are secular, clinically based methods that employ manuals and standardized techniques. Studies indicate that MBSR and MBCT have broad-spectrum antidepressant and antianxiety effects and decrease general psychological distress. MBCT is strongly recommended as an adjunctive treatment for unipolar depression. The evidence suggests that both MBSR and MBCT have efficacy as adjunctive interventions for anxiety symptoms. MBSR is beneficial for general psychological health and stress management in those with medical and psychiatric illness as well as in healthy individuals. Finally, MBSR and Zen meditation have a role in pain management.